Mental toughness and an aptitude for sport may be biologically determined. This is one of the findings of an ongoing research project involving post-doctoral and doctoral research by Dr Jim Golby and Jennifer Meggs from Teesside University.

Previous research found that finger length could predict everything from penis size to prostate cancer and even heart attack risk. Now, researchers will present their work at the Division of Sport and Exercise Psychology's Annual Conference that has the potential to explain sporting success and mental toughness.

It has been known for some time that there is a direct correlation between finger lengths and the amount of the male sex hormone testosterone that a baby is exposed to in the womb.

This research investigated the relationship between 2D:4D and mental toughness, optimism, aggression and performance.

Sixty-seven participants had their fingers measured and completed personality and aggression questionnaires.

The results showed that participants with 2D:4D ratio were more likely to demonstrate mental toughness and have higher levels of sporting achievements.

Dr Golby explained: "It appears that high prenatal levels of testosterone may result in increased mental toughness, optimism and hence aptitude towards sport. This provides tentative support for the conclusion that mental toughness may be partially biologically predetermined."

In women, the two fingers are usually almost equal in length, as measured from the crease nearest the palm to the fingertip. In men, the ring finger tends to be much longer than the index.

Other studies looking at finger length ratio have suggested that, in men, a long ring finger and symmetrical hands are an indication of fertility, and that women are more likely to be fertile if they have a longer index finger.

One study found boys with shorter ring fingers tended to be at greatest risk of a heart attack in early adulthood, which was linked to testosterone levels.